Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
  • C21D8/0436—Cold rolling

Definitions

• the invention relates to a method of manufacturing a steel strip intended for the production by stamping and re-stamping of steel containers.
• cold rolled strips of low carbon steel or ultra low carbon steel are used which are transformed by stamping / re-stamping.
• the strips are obtained from hot rolled strips which are cold rolled a first time then annealed and then cold rolled a second time, the second cold rolling is carried out in a single pass which produces a reduction in thickness of approximately 40%.
• the strips thus obtained have a thickness greater than or equal to 0.18 mm, a tensile strength less than 600 MPa, and a satisfactory drawing ability.
• the object of the present invention is to provide a process for the manufacture of cold-rolled steel strips, having good drawing ability while having a tensile strength greater than 600 MPa and a thickness which may be less than 0 , 18 mm.
• a thickness reduction of at least 35% is carried out.
• the second cold rolling can have two passes, and in this case, during the first pass, a thickness reduction of at least 25% is carried out and during the second pass, a thickness reduction of at least 5%.
• the thickness reduction carried out during the second cold rolling is between 38% and 47%, and the annealing is often carried out between 600 ° C and 700 ° C, the annealing can be carried out continuously.
• the thickness of the strip may be less than 0.17 mm.
• the inventors have found, quite unexpectedly, that when a cold rolled strip of steel of the ultra low carbon type is manufactured, obtained from hot rolled strips cold rolled a first time then annealed and then cold rolled a second times, and when the second cold rolling is carried out in two passes instead of a single pass, it was possible to obtain all at the same time, a small thickness, a high mechanical strength and a good drawing ability.
• thin thickness means a thickness less than 0.20 mm, and preferably less than 0.17 mm; by high mechanical strength is meant a tensile strength greater than 600 MPa; by good drawing ability is meant a horn rate C of between 0 and -0.4, and an anisotropy coefficient r close to 2 (between 1.5 and 2.5).
• a hot rolled strip is produced, in known manner, which is then cold rolled to obtain a cold rolled strip (blank), of thickness between 0.2 mm and 0.3 mm.
• This blank is then annealed continuously between 600 ° C and 700 ° C and preferably between 630 ° C and 680 ° C.
• the annealed blank is then subjected to a second cold rolling comprising at least two passes carried out on a continuous rolling mill.
• the reduction rate of the first pass must be greater than 30% and the reduction rate of the second pass must be greater than 5%; the total reduction rate must be between 35% and 50%, and preferably between 40% and 45%.
• Cold-rolled strips are thus obtained which are particularly suitable for the manufacture by stamping / re-stamping of steel containers of the beverage can type, the characteristics of which are indicated above.
• Annealing was carried out at 650 ° C; during the second cold rolling, the reduction during the first pass was 30% and during the second pass the reduction was 10%.
• the tensile strength of the strip was 675 MPa, the rate of horns measured by the magnetic anisotropy method was -0.36 and the rate of anisotropy r measured by the texture RX method was 2.01 .
• Annealing was carried out at 650 ° C; during the second cold rolling, the reduction during the first pass was 30% and during the second pass the reduction was 8%.
• the tensile strength of the strip was 635 MPa
• the rate of horns measured by the magnetic anisotropy method was -0.25
• the anisotropy rate r measured by the RX texture method was 2
• Annealing was carried out at 650 ° C; during the second cold rolling, the reduction during the first pass was 20% and during the second pass the reduction was 10%.
• the tensile strength of the strip was 626 MPa, the rate of horns measured by the magnetic anisotropy method was -0.42 and the rate of anisotropy r measured by the texture RX method was 1.5.
• Annealing was carried out at 650 ° C; the second cold rolling was carried out in a single pass with a reduction rate of 45%.
• the tensile strength of the strip was 599 MPa
• the rate of horns measured by the magnetic anisotropy method was -0.34
• the rate of anisotropy r measured by the texture RX method was 2.09 .
• Annealing was carried out at 650 ° C; the second cold rolling, carried out in a single pass, the reduction rate was 30%.
• the tensile strength of the strip was 599 MPa
• the rate of horns measured by the magnetic anisotropy method was -0.46
• the rate of anisotropy r measured by the RX texture method was 1.5
• the examples according to the invention are a combination of tensile strength and rates of horns and anisotropy coefficients which clearly show the advantage of the invention compared to the examples of the prior art given by way of comparison.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Heat Treatment Of Steel (AREA)
• Press Drives And Press Lines (AREA)
• Package Frames And Binding Bands (AREA)
• Metal Rolling (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9470010

Family Applications (1)

Country Status (10)

Cited By (4)

Families Citing this family (3)

Citations (5)

Family Cites Families (1)

• 1994
  • 1994-12-21 FR FR9415350A patent/FR2728490B1/fr not_active Expired - Fee Related
• 1995
  • 1995-12-07 DE DE69515010T patent/DE69515010T2/de not_active Expired - Fee Related
  • 1995-12-07 PT PT95402752T patent/PT718411E/pt unknown
  • 1995-12-07 ES ES95402752T patent/ES2144591T3/es not_active Expired - Lifetime
  • 1995-12-07 AT AT95402752T patent/ATE189704T1/de not_active IP Right Cessation
  • 1995-12-07 EP EP95402752A patent/EP0718411B1/de not_active Expired - Lifetime
  • 1995-12-19 CA CA002166565A patent/CA2166565A1/fr not_active Abandoned
  • 1995-12-19 JP JP7348755A patent/JPH08224602A/ja not_active Abandoned
  • 1995-12-21 US US08/576,368 patent/US5704997A/en not_active Expired - Fee Related
• 2000
  • 2000-04-06 GR GR20000400858T patent/GR3033166T3/el not_active IP Right Cessation

Patent Citations (5)

Non-Patent Citations (1)

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